David Sulzer, a neurobiologist at Columbia, led a study that may help explain symptoms of autism like oversensitivity to noise, as well as why many people with autism also have epilepsy
As a baby’s brain develops, there is an explosion of
synapses, the connections that allow neurons to send and receive signals. But
during childhood and adolescence, the brain needs to start pruning those
synapses, limiting their number so different brain areas can develop specific
functions and are not overloaded with stimuli.
Now a new study suggests that in children with autism,
something in the process goes awry, leaving an oversupply of synapses in at
least some parts of the brain.
The finding provides clues to how autism develops from
childhood on, and may help explain some symptoms like oversensitivity to noise
or social experiences, as well as why many people with autism also have
epileptic seizures.
It could also help scientists in the search for treatments,
if they can develop safe therapies to fix the system the brain uses to clear
extra synapses.
The study, published recently in the journal Neuron, involved tissue
from the brains of children and adolescents who had died from ages 2 to 20.
About half had autism; the others did not.
The researchers, from Columbia University Medical Center,
looked closely at an area of the brain’s temporal lobe involved in social behavior
and communication. Analyzing tissue from 20 of the brains, they counted spines
— the tiny neuron protrusions that receive signals via synapses — and found
more spines in children with autism.
The scientists found that at younger ages, the number of spines
did not differ tremendously between the two groups of children, but adolescents
with autism had significantly more than those without autism. Typical
19-year-olds had 41 percent fewer synapses than toddlers, but those in their
late teenage years with autism had only 16 percent fewer than young children
with autism.
